Homogeneous dispersion and mechanical performance of aluminum reinforced with high graphene content

Abstract

In this research, trials were performed to improve the mechanical properties of pure aluminum, maintain its lightweight, and enhance the distribution of graphene with high content up to 1.5 wt%. Aluminum composites reinforced with 10% copper, 2.5% alumina, and different ratios of graphene up to 1.5% were manufactured by powder metallurgy followed by hot rolling. The suitable sintering conditions were 565°C for 60 min under a vacuum atmosphere. The powder metallurgy method showed a general improvement in aluminum’s microstructure. An excellent distribution of the different reinforcements was achieved up to 1.5 wt% GNs due to the long mixing time in the hexane solution. However, some aggregations of the GNs layers were observed at 1.5 GNs percent. The mapping analysis detected the nano-alumina distribution. The 1 wt% GNs sample exhibit the greatest improvement in hardness with 2.4 times and yield strength increment with 76% compared to pure aluminum. Also, the wear rate decreased significantly at 1 wt% GNs percent. By conducting the hot rolling process, all results exceeded their counterparts by the powder metallurgy method up to 1.5% GNS content. The accumulated GNs at 1.5 GNs percent were spread due to slipping them over each other as a result of the rolling process. Eliminating the internal pores and improving the distribution of graphene in that sample improved its hardness, yield resistance, and mechanical wear. After the rolling process, the hardness at 1.5 wt% GNs increased from 218 HV to 389 HV, and the yield strength from 203 MPa to 280 MPa.